1. The Field of the Invention
The present invention pertains to antennas, including radio frequency antennas of generally cylindrical construction, either as a linear or as a branched structure. More specifically, the present invention relates to antennas constructed from a composite structure of metal coated structural or reinforcing fibers or non-metal coated structural/reinforcing fiber composites with metal additives in the composite's polymer matrix.
2. The Relevant Technology
Historically, radio frequency antennas have been of several various constructions. In a first type of construction, antennas are composed of metal tubes. These antennas act as an efficient conductor of electrical energy. The disadvantage of such antennas, however, is that they are quite heavy, not very flexible, and are relatively easy to bend and, thus, break. A second type of antenna construction is comprised of structural fiberglass tubes with conductive wires extending downwardly through the tubes as the electromagnetic receptor. Relative to metal tubular antennas, fiberglass antennas are slightly more flexible and lighter in weight. A third type of antenna construction uses carbon/graphite fibers, which are somewhat conductive. However, carbon fiber composite systems alone are generally not sufficiently conductive to perform as well as an antenna. As such, additional materials must be added for the carbon fiber system to function satisfactorily as an antenna. In a fourth construction, an antenna is made from a combination of short fibers dispersed into a thermoplastic or thermoset polymer.
In recent years, a further antenna construction has been developed. This construction is composed of carbon fibers plated with nickel by either an electroplating process or electro-less process. However, antennas of this type of construction still require that other conductors, such as a silver film, be disposed over the nickel film for the antenna to perform in an acceptable electrically conductive manner. Accordingly, a need exists for materials, or a combination of materials, that can be used to construct a relatively light weight antenna with sufficient electric and electromagnetic properties.